Summary: someone did a survey of 800+ transhumanists to rank 7 possible scenarios by which we can achieve immortality, on a scale of 1-7. The top three, in an effective tie, were: The Singularity (4.37), Nanotechnology (4.37) and Genetic Engineering (4.35). None of the 7 had a value less than 3.0. Now you don't have to read the link. You're welcome.